CYP2C19 and transient ischemic attack: There were 20 cases of stroke or transient ischemic attack within 90 days, including 15 cases of CYP2C19 gene deletion, 5 cases of CYP2C19 gene carriers, 8 cases of vertebrobasilar artery extracranial stenosis, and 12 cases of vertebrobasilar artery intracranial stenosis.